Aircraft: COMMERCIAL FIXED WING
Phase of flight: Taxi
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway

Initially planned 09R Dep as per Flight Plan and current ATIS. Briefed RANUX4G Dep. After obtaining clearance and new ATIS; Departure Runway was changed to 27L. Runway change procedures followed and new briefing for the RANUX4A from 27L briefed; FMS perf verified; data changed etc. While taxiing out we were told to contact GND at spot (removed). We did so and were given instructions to taxi; Spot; Q RWY27L. A discussion ensued with all 3 pilots about whether or not this allowed us to choose our own route to 27L. During this time I slowed to a taxi speed of about 4-5 knots; barely rolling; to give everyone a chance to absorb the call and catch up. We decided to err on the side of clarity and asked if we could taxi Spot; B; Q4; 27L. The answer back was no. What I heard was: Taxi Spot; BD8; D; Q; 27L. Ok; upscale the iPad and look for the route. Everyone else was doing the same. I was having a problem finding BD8; verbalized it and the RFO said I'll give you 'progressive'. We were still going less than 10 KTS when I made the turn to follow M in front of the Fire Station. Because of the lighting; signage; and the fact that I undershot the turn to stay on M; we rolled barely onto MD2. As soon as I realized my error; I stopped (cursed) and set the brake. I told the crew what happened and that we could not make the turn back to M and we would be unable to make a right turn onto any other taxiway to continue east bound. At that time; Ground called and told us that it appeared we undershot our turn and were on MD2. We agreed and asked what she wanted us to do. We were given a standby. During that time we discussed the only way out was to continue on MD2; MD1D; BD6; B and get going the other way. Ground came back on and asked if we could do exactly that. We concurred and we were given that exact clearance plus from B; BD9; Q; Q4 to 27L. It is nitpicking but I don't believe QD1 was ever given between D and Q. In any event. We got turned around. Didn't turn in a prohibited direction; didn't drag a gear truck through the mud or non-stressed area; didn't have to get towed and didn't shut down any taxiways or inhibit any other aircraft from their taxi. We got everyone on the same page and taxied to the end and took off. Once in the air; we debriefed the event as a crew. The initial taxi instructions were vague. The subsequent taxi instructions became confusing. The FO apparently didn't understand the taxi instruction; confusing BD8 for B; D8. I couldn't find BD8 on my chart while scaling up and sliding the chart around to understand the route. The RFO thought he had the route clarified only to lose the bubble at the end and was unable to communicate clearly what he was seeing. The signage in that area is abysmal. The lighting is glaring and the markings on the taxiways are not very clear/faint. And in our case; by the time we could verify our position; it was too late to fix it.With ongoing construction and changes at CDG; with being there previously and given taxi down B to QB7; Q4; 27L; etc. Even though we reviewed the taxi options and the standard taxi pages; we were given something unexpected and were unable to resolve what should have been a simple problem. I didn't realize how much of a problem it was until I undershot M on M2. I thought we had it resolved. I should have stopped; set the brake and sorted it out. Something that would also help would be to have ATC give instruction similar to ' Taxi from spot M via North Route 22; hold point XXX; RW27L'. We try to not set expectation bias by briefing TAXI routes. When they are given piecemeal instead of as a package; it gets confusing sometimes. We were finally able to alleviate these issues in CAN with canned routes. Not finger pointing; just a suggestion. It was my fault. I was second RFO seated in the back in supernumerary seating; by the galley. I did notice some conversation after stopping then a left turn and some extra taxi movement and instructions. I was not seated in the cockpit during taxi out. Later I was told by the crew there was some confusion as to the finding the correct taxiway in which they were cleared. I know from experience that Paris taxi markings and lighting is subpar. There have been other occurrences in this same location. I even remember a hot topic published outlining the difficulties in taxiing in this area. Other flights have turned right onto delta and have left the prepared [surface]. I give accolades to this Captain for not falling in this trap after he had missed the correct turn on the correct taxiway. His actions saved the jet from leaving the prepared surface and allowed the flight to continue to destination and delivery of the freight; albeit with a few extra taxi clearances needed. Paris should take responsibility for these occurrences and get their taxiways up to par standards. The rest of the flight was uneventful. I believe [the cause] was confusion with taxi instructions and unable to discern the proper taxiway. My understanding is they did the right thing they were confused; they stopped the jet and figured out the problem. Then proceeded with an adequate solution. Flight Crew reported unclear taxi instructions which resulted in an incorrect turn on a taxiway at CDG; Charles De Gaulle Airport.